Field of the Invention
The present disclosure relates generally to a device and method for separating higher and lower density fractions of a fluid sample and, more particularly, the present disclosure relates to a device and method for rapidly separating higher and lower density fractions of a fluid sample without the need for a centrifuge or other high-cost equipment.
Description of Related Art
Diagnostic tests may require separation of a patient's whole blood sample into components, such as serum or plasma (the lower density phase components), and particles and aggregates such as red and white blood cells and platelets (the higher density phase components). Samples of whole blood are typically collected via venipuncture through a cannula or needle attached to a syringe or an evacuated blood collection tube. After collection, separation of the blood into serum or plasma and blood cells is typically accomplished by centrifugation of the whole blood. More recently, there has been an effort to separate plasma using microfluidics. However, these approaches are limited by requirements of dilution and the total volume of blood that can be processed.
Another common method used for processing micro samples of blood is the lateral flow separation method wherein a blood sample moves through a strip of filter material in a lateral direction. However, the total surface area to volume requirements of the material, when using this method, limits the total volume of blood that can be processed.
Another technique for separating plasma from a whole blood sample is simple filtration which allows the blood sample to flow via capillary forces through a filter wherein the filter includes pore sizes which are smaller than the size of the cellular particles or red blood cells. This method is commonly referred to as conventional size exclusion filtration. In this method, the filter traps the cellular particles or red blood cells so as to separate these particles/cells from the serum or plasma portion. However, one drawback to this method is that the filter can become blocked, thus hindering movement of the whole blood sample therethrough and, thus, slowing and/or reducing the collection of the plasma portion of the sample.